Problem: Some cars were parked in the gift store parking lot. 5 more cars park at the gift store. Now there are 23 cars in the parking lot. How many cars were parked at the gift store at the beginning?
Solution: The number of cars parked at the store at the beginning is the difference of the number parked now and the number that came and parked earlier. The difference is $23 - 5$ cars. $23 - 5 = 18$ cars.